 | Figure 1
Nature Biotechnology 24, 325 - 326 (2006)
doi:10.1038/nbt0306-325
The selfish stem cellPeter W Andrews | | | | Figure 1. Generating the 'selfish' stem cell.
(a) When they divide, stem cells have a choice between three possible fates: death through apoptosis, differentiation, or the generation of a new stem cell, a process we call 'self-renewal.' Pyle et al. have identified neurotophin signaling as a significant part of the decision machinery whereby human ES cells choose between these fates: specifically, neurotrophins appear to block the apoptotic fate. (b) Elements of the decision process are likely to be key targets for mutation and selection pressure to generate variant ES cells that develop over time in culture. Mutations that promote self-renewal at the expense of death or differentiation will provide the variant stem cells with a selective advantage, and so promote maintenance and expansion of the stem cell population. Such variants are likely to tend towards the transformed phenotype of tumor stem cells. Indeed, it can be envisaged that ES cells in culture are part of a continuous spectrum of adaptation from a 'normal' state of cells within the inner cell mass of an embryo, through cultured ES cells, to the state exemplified by malignant pluripotent stem cells from teratocarcinomas, the EC cells. Herszfeld et al. have shown that the appearance of CD30, which plays a role in suppressing apoptosis, seems to mark a stage in this progressive process of adaptation.
Bob Crimi |
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